Three dozen bridges in 21 states may have been built with defective grout. The FHWA is now examining corrosion and chloride levels in several of them.

Sampling and Testing

The heads of the Maryland and Virginia transportation departments have expressed concern about the issue in a letter to U.S. Secretary of Transportation Ray LaHood. The letter cited the Woodrow Wilson Bridge, which carries I-95 over the Potomac River.

Federal and state highway officials say there is no imminent hazard, according to The Baltimore Sun. The FHWA said the presence of chloride is not an indication of corrosion but "does indicate corrosion potential."

Federal officials are currently conducting tests to determine the long-term effects of chloride-contaminated grout on steel cable.

Chloride and Grout

In October, Paul Kelley, PE, Senior Principal at Simpson Gumpertz & Heger presented the "Interim Report on Investigation of Impacts of Chloride in Post Tensioning Grout" at Kansas State University during the 19th Annual Bridge Design Workshop.

Accoding to Kelley's update, the scope of the investigation as of Oct. 5 has included:

Sampling 10 bridges with easily accessible tendons spanning the full production period to determine if contamination risk as time boundaries;

Determining if manufacturing records of cement supplier and Sika can define high chloride production dates; and

Determining critical chloride content.

A total of 439 samples have been tested; 321 are field samples and 118 are retained samples, Kelley reported. Out of the samples, 59 percent have acid-soluble Cl- by weight of cement greater than 0.08 percent, which is the FHWA's specified limit.

Paul Kelley / KSU

At the 19th Annual Bridge Design Workshop in October 2012, updates were provided on the investigation into bridges built with grout containing excessive levels of chloride.

Kelley also discussed the objectives of FHWA's Accelerated Corrosion Testing, which included:

The presentation also outlined future work on the invesigation. A preliminary data comparison with FHWA was planned for completion in November 2012.

A FHWA representative could not yet confirm if this data comparison has been completed.

After testing is completed, the next steps for guidance on allowable critical chloride levels will be planned with the FHWA Stakeholders Group based on the sampling results.

Sika has hired a team of independent experts to analyze potential risks and make recommendations and has instituted new quality control testing before grout is shipped to contractors, said Diana Pisciotta, Sika spokesperson, according to The Baltimore Sun.